Regulating system



Nov. 27, 1928. 1,693,307

G. R. MCDONALD REGULATING SYSTEM gFiled Feb 5, 1926 L/s k I L I J l ML L 20 8 g /3' T Inventor: Gordon IQ. McDgnald;

His Anborneg- Patented Nov; 27

or-rlc E;

- eonnonnz MCDONALD, or scHEnEcTAnY, n'nw yonx; nssrenon 'ro GENERAL ELEC- ERIC, COMPANY; nconronn'rronor new YORK.

' ImGnLA'rING SYSTEM:

A iplicat on filed rbriiar 5, 1926. Serial No. 86,329.

' My invention relatestoregulating systems for maintaining a predetermined division load between a plurality, of parallel machines and. itsobject s to provide unimproved: sys= tem ,foracconiplishingthis result.

My. invention istespecially, applicable. to a regulating system for maintaining. the load properly divided between a plurality of overcomppunddiiect current generators connected toacommon network. a I

My. invention: will be better understood fromnthefollowing description taken in connection with the accompanying drawing,- and its .escope iwill bepfointed :outin the appended showsmy invention in. connection with. a, load regulatinggsystem for two, overcompounddidterminedzconditiom f u ,o I

Each generatoryis provided with the usual ample, each, means may; form a part of V an an tom atie switching equipment, exan ples of which are well known in theart, whereby; it is closed automatically afterithe'respective generator has be'enst'arted and has reacheda-pres series, commutating, and shunt: field windings.) As showninthe'dfawingsflsancl 8 are theseries field windings, 9and '10 are the cominutating Lfieldf and ll, and 12'fa're the. shunt lieldwindings of thegeneratorsy 1 ,and'2respectively. v v

13represents anyisuitable switchingmeans which, when closed, completes an equalizing connectionbetween: the two series field "wi'ndings so that substantiallyequal ,currents flow through the seriesfield windings. Itis prefe r'ableiinlsomecases to'cornplete this connecv Ytion only afterbothmachines are connected in parallel Therefore, Ihave shown the circuit of theclosing. coil ofltheswitch 13asineludingmauxiliaryv contacts-on the switches 4 and 5, so thatthe: switch 13 can-be closed only when .both of the switches 4 \5 are as o t,

closed It may be desirable, however; in a other cases, to complete theequalizingcOnnectionbeforethe two machines are connect-1 ed in; parallel and this maybe done in the arrangement shown by omitting the auxiliary contacts of the switches 4: and 5 from the Cir cuitoffthe, closing coil of the switch; 13 and providing any other suitable switching means, which may be eit-liermanually or au-, tolnatically controlled, to open and close the, ei-rcuitiof the closing coil of the switch '13 at the proper time. i

For, equalizing the loadson the two generators, suitablecurrent limitingnieans, shown as resistors; 15 and 16-, arerespectively'provided inthepcircuits of the field windings ll and 12, and a polarized relay 170i any suitabletype, examples ofwhich are well known in the; art, is provided for selectively controllinga short circuit around eacliresistor in, accordancev with the relative current out puts ofthe two generators.

"As shown in the drawing the polarized relay175 comprises an armature 18 pivotally mounted within the two windings 19, and 2Q which are-therefore'in mutual inductive rela: tionl, The mutually inductive windingslE) and 20 are wound diilerentially with. respect to each other and are respectively connected so as tobe energized in accordance with the current tit-puts; of thegenerators Land 2. As shown in the drawing, the windinglS) is connected inparallel with the conimutating winding 9 and the winding 20 is connected in parallel "with, the connnutatingu winding 10, The

armature 18 also is pivoted between the polar projections of a stationary magnetic member 21so: that the'armature occupies different positionsdepending upon the direction and magnitudefof the resultant magnetomotive force produced by the currents throu h the windings 1'9 and 20.- The armatureis iased to theposition shown in the drawing-so that 22 t'o retl' er. thereby completing a short circuit around the resistor 16 hen, the ampere turns of ;the.winding;19 are less than the when theampere turns of the two windings ampere turns of the winding 20 by a predetermined amount, the direction and amount of thin in the armature 18 is such that the armature is moved to the left and connects the contacts 23 together, thereby completing a short circuit around the resistor 15. windings 19 and 20 are designed so that their ampere turns are substantially equal when the load is divided in the desired manner between the two machines.

The magnetic member 21 may be a permanent magnet but preferably it is magnetized by means of a magnetizing winding 25, the circuit of which is arranged to be completed across a suitable source of direct current of definite polarity, such as the network 3. Suitable adjustable rheostats 28 and 29 may be provided in the circuits of the shunt field windings 11 and 12 respectively, whereby the voltage of the generators may be regulated. The adjustments of these rheostats may be controlled either manually or automatically in a manner well known in the art. The operation of the system shown in 1 is as follows: hen only one generator is in operation, the switch 13 1s open so that the winding 25 and the current winding associated with the generator in operation are the only windings ofthe relay 17 that are energized. For example, if the generator 1 is the machine supplying current to the network, the current winding 19 and the winding 25 of the relay 17 are energized. The energization of the current winding 19, under such conditions, causes the relay 17 to close its contacts 22 and tiereby short circuit the resistor 16 in the circuit of the field winding 12 of generator 2. Since the generator 2 is not connected to the network, the short-circuiting of the resistor 16 hasno, eiiect at this time, but when the generator 2 is being started the fact that the resistor 16 is short circuited causes the machine to build up its voltage more quickly.

hen the second machine is connected to the network 3 and the auxiliary'contacts 30 and 31 on the circuit breal rs 1 and 5 complete the circuit of the closing coil of the switch 13, the relay 17 then operates to control the division of the load between the two machines. If the current output of the generator 1 is too great relatively to the current output of the generator 2, the relay 17 closes its contacts 22.- thereby increasing the excitation of the generator 2. This increasein the excitation of the generator 2 increases its currentoutput and thereby decreases the current output of the generator 1. hen the current output of the generator 2 has been increased suflic-iently so that it as at the proper value relatively to the output of the generator 1, the relay 17 then operates to open its contacts 22 which remain open until the output of the generator 2 again decreasesrelatively to the output of the generator 1. If the current output of the generator 2 is too great relatively to the current output of the generator 1, the relay 17 closes its contacts 23 to effect an increase in the excitation of the generator 2 until desired current balance is restored when the relay 17 opens its contacts Tests have shown that by means of my improved arrangement it is possible to operate in parallel two m'ercouzpmmd (lll'fif? current generators which have materially ditlei ent volt-ampere.characteristics and maintain the load divided between the two niechines in the desiredmanner for all values of load. lVhile I have described the arrangement shown in this figure controlling the outputs of two machines 1 ant 2 so as to mainrain a predetermined division between the outputs thereof, this arrangement is also arranged to maintain the desired relation between the current supplied to the two machines when they receive current from the load circuit. For example, assume the two machines 1 and 2 are connected to the circuit 3 and are receiving current therefrom and the current supplied to the machine 1 is greater than the current supplied tothe machine 2. Under these conditions the ampere turns of the windingll) of the polarized relay 17 exceed the ampere turns of the winding 20. Since, however, the currents through these windings are in the opposite direct-ions from what they are when the machin s 1 and 2 are supplying current to the load circuit, the resultant flux produced in the armature 18 of the polarized relay 17 is also in the opposite direction. Therefore, the relay 17 operto close its contacts instead of its contacts 22. The closing of the contacts 23 effects in the manner heretofore described an increase in the excitation of the machine 1 so that the amount of current supplied to the machine 1 is decreased.

In a similar manner, if the current supplied to the machine 2 exceeds the amount of current supplied to the machine 1, the polarized relay 17 operates to close its contacts 22 and eifects n increase in the excitation of the machine 2 so as to decrease the amount of current sup lied thereto.

The relay 17, theretore, operates to maintain the proper division of current between the two machines whether the machines are supplying current to the load circuit or receiving current from the load circuit.

In the modification of Fig. 1 shownin Fig. 2, the two current coils 19 and 20 of the regulating relay 17 are connected in series in the equalizer connection. It will be observed that by means of such a connection the direction and magnitude of the flux in the armature 18 varies in accordance with the relative current output of the two machines in the same manner in Fig. 1. lVhenthc generator 1 is supplying more than its share of the load,

the voltagedrop'across theiseries field winding 7 is greater thanithe voltage drop. across thefield Winding 8; Therefore, current flows tlirough 'the'equalizer connections and, the

currentcoils1'9 and from the field Wind'- ing 7 to the field Winding8. The direction of the current through the current coils 19 and V 2(lunder these conditionsissuch' as-tocause the relay 17 to 'closeits contacts 22, thereby efi'ecting an increase in the current output of: the generator 2.to restore' the proper division oflthe" load. between theiltwo generators.

WVh'en the generatoril.is supplying more than itsshare of the load, the "voltage drop'across i thelwindings 19 and'20'ot the relay'17 isa-lso the series fieldwinding -7 is less than the voltage drop across the series field winding 8.

Consequently, current: flows through the equalizer connectionand the current coils 19 and 20 in the opposite direction so a thatv the" relay 17 closes'its contacts 23', thereby 'etfcct ing an increase in thecurrent output ofthe genera-torl'lto restore the proper division of the load betweenthe two generators; The

arrangementshown in Fig. 2is alS0 arranged to ma ntain the proper (l1V1S10I1 l)el3QBI1nth currents through the machines 1 and 2iwhen's they receive current from theloadcircuiti3.

For cxam'ple if the'current' suppliedto the machine l exceeds the current .supplied to, the machine 2 the-polarizedrelay17 opcr+- ates to closeits contacts 23instead ofits contacts 22 since'th'e voltage drop across the Winding 7 while greater than the voltage" dropacross" the Winding'S, is in the opposite direction from What-it'is'whenthe machine 1 is supplying the greater current to the load circuit; Consequently, the C1lIIfI1t"tl1I0Ugl1 in the opposite direction so-th'at the'fiuxuprm duced'in the armature o-f 'the polarized relay 171s in a direction to cause the relay tozclose a its contacts 23; "The'cl'osingof the-contacts efiects' an increase in the excitation. of the machine-1. In :l'Slli'illZll manner the relayl'? operates to closeits contacts22'toeiiect an increase "in the excit'ation ofthe machine 2 when the current supplied to *the machine 2 vexceedstheamount supplied to the machine 1.

While "I have in accordance with the pat cnt statutes shown and described my invention as appliedZtoa particularsystein and as embodyingvarious devices diagrammatically indicated} changes andmodificationswill be lit) obvious to-thoseslrilled in'the art, and I therefore aim in the appended claims to cover all suchclianges and mo dificationsas fall within the true spirit and scope of myinvention, VWiatIclaim as nei'v an'ddesire to secure by Letters Patent" of the United States, its 1.. In a regulating system, two direct current generators connected in parallel. I field circuit for each generator, current limiting means in each field, circuit, and a polarized relay connected and arranged so that when the current output of one of said generators is: too great :relatively to the currentoutput oi the othergen'crator, sald polarized relay occupies a position to decrease the amount of cuirent liiniting means in the field cii'cuitiof sa d other' g enerator and when the current output of said one of said generators is too,

small relatively to the current output of said other generator; said polarized relay occupies a position to decreasethe amount of current limiting meansin the ficldcircuit of said one of saiduvgencratorst a regulatingsystem, two generators connected in parallel, and apolarizedrclay for-controlling the excitation of one of said generators comprising two mutually inductives diltcrentially'wound windings rcspectivclyenergized in accordance with the cur-W rent outputsofzthe two generators.

' In a regulating system, two direct cur rent generators connected in parallel, each generator being provided with a series'connested field winding; and a'polarized relay for controlling the excitation of one of said gen 'cra'tors comprising asmagnetic iii-ember and two differentially wound windings around said 'meinber"respectiyely connected in parallel with said series connected field windings.

In 'comhinationytwo dynamoelectric inachines com c ted inparalleh polarized relay arranged when in one position to effect a change. iii-the excitation of one of said-nia- ,chines and when in another position to-cfl ect a change inthe excitation cit/the other of said niachines and means for producing :a in' q'neton'iotive iorcein'said relay which varies in direction and magnitudein accordance withthe difference-between the-loads of the. two machines whereby said relay ismoved into one of said positions when the load on onc ofraid machinescxceeds the load on the other and 1s moved into the other of said positions when thelcad on said one-of said r'nachines is less than the loa'd'on theother;

Ina load regulating. systenii'for two direct currentgenerators connected in parallel, a polariiecl relayarranged when in ,oncpcsition to ease acha nge inthe'excitation oi? oi the generators and when in another position to effect a change in the excitation of the other generator, and meansvlor produc ng a maqnetoinotive forcein said relaywhic ari in directionand niagnitudein accord nce with the difference between the current outthe other of said windings being connected so that it is energized in accordance with the current output of the other generator.

6. In a load regulating system for two overcompound direct current enerators connect-- ed in parallel, the combination of a resistor in the shunt field circuit of each generator, a polarized'relay arranged when in one position to eliect the short circuiting of one of said resistors and when in another position to effect the shortcircuiting of the other resister, and means for producing a magnetomotive torce in said relay which varies in direction and magnitude in accordance with. the difference between the current outputs of the two generators, whereby said relay moved to one of said positions when the current outa put of a predetermined one of said generators exceeds the current output of the, other generator and is moved to the other position when the current output of said predetermined one of said generators is less than the current output of the other generator.

'7. In a load regulating system tor two compound direct current generators connectcd in parallel. the combination of a resistor in the shunt field circuit of each generator, and a polarized relay arranged when in one positlon to effect the short circuiting of one of said resistors and when in another position to etiect the short circuiting of the other resistor, said relay having two ditlercntially wound windings respectively connected in parallel with the series connected fieldwindin gs of the two generators whereby said relay moved to one of said positions when the current output of a predetermined one of said generators exceeds the other by a predetermined amount and said relay is moved to the other of said positions when the current output of said predetermined one otsaid generators is less than the other bya predetermined amount.

8. In a regulating system, two overcompound direct current generators connected in parallel, current limiting means in the field circuit of each generator, and ,apolarized relay controlled by the relative current outputs of the two generatorstor selectively short circuiting the current limiting means in the field circuit of the generator furnishingthe smaller current. V

9. In a load regulating yttem for two dynamoelect-ric machines operating in parallel, the combination of current limiting means in the field circuit of one of said ma hines, and apolarized relay for varying the amount of said currentlimiting means in said field circuit comprising means for producing main magnetomotive force, a magnetic member and means for producing in said magnetic member an auxiliary magnetomotive force whose direction and magnitude vary directly with the difference between the outputs of the machines, said magnetomotive forces and said magnetic member cooperating to cause said relay to efiecta decrease in the amount of current limiting means in the field circuit only when the output of the other machine exceeds the output of said one of said machines.

10. In a load regulating system for two dy namoelectric machines operating inparallel, the combination of current limiting means in the field circuit of one of said machines, and means for varying the amount of current limitingmeans in said field circuit comprising a polarized relay having a magnetic member and: means for producing therein a magnetomotive force whose direction and magnitude vary directly-with the difierence between.

12. In a regulating system. an electric circuit, two dynamoelect-ric machines connected in parallel across said circuit and a polarized relay responsive to the direction-and relative magnitudes of the currents flowing through the two machines for effecting a predetermined change in the current through one of the machines when it is supplying to said circuit a greater current than the other machine is supplying and a similar change when said one of said machines is receiving from said circuit a smaller current than the other machine is receiving.

13.'In a regulating system, two dynamoelectrie machines connected 1n parallel. and a polarized relay for controllingtheexcitation oi? one of said machines to maintain a predetermined relation between the currents flowing through said machines comprising two mutually inductive differentially wound windings respectively energized in accordance with the currents flowing through the two machines.

In witness whereof, I have hereunto set my hand this 4th day ofFebruary, 1926.

GORDON R. MCDONALD. 

